Audio VU Meters & Raspberry Pi

I started building a small NAS from scrap parts such as some old HDDs and a Raspberry Pi. Assembling the parts and installing the software was rather simple, but putting it into a nice enclosure that also shows what the headless device is doing was a bit more complicated. I always fancied analog displays on old Hi-Fi equipment and find it a bit sad that everything is being with digital displays in the recent years. Therefore, I wanted to use old fashioned analog VU meters to display the network bandwidth usage and CPU activity of the device. Sadly, there was no pre-built solution for this. So I had to create my own.

Implementing this idea required me to learn interfacing Python on a hardware level, which was very interesting. The Raspberry Pi doesn’t have a native DAC so I bought a nice little MCP4922 DAC chip and got started with wiring it up and programming a driver.

It took me about two weeks to make it work perfectly and it was a rewarding experience to see the final outcome in action. I had the enclosure laser-cut out of wood from a random shop on Taobao. This was super cheap (around USD 10 – 15) and convenient, as I don’t have any wood working tools here in Hong Kong. The box design is just simply plugged together and then fastened with some small screws and nuts.

As there was no documentation on a similar project before, I wrote a beginner friendly tutorial and published it on hackaday.io.